Suchergebnisse

ABSTRACTBiological aerated filters are wastewater‐treatment systems which contain support media for the development of a biofilm and provide oxygen at the base of the reactor for aerobic microbial processes. The origins of this type of filter date back to the early 1900s, and modern designs can provide a high level of treatment in small reactor 'footprints'.This paper provides a review of the technology and development of biological aerated filters and submerged aerated filter systems.

AbstractThis paper describes the performance of a small packaged plant serving about 70 people and incorporating submerged aerated filters. The diurnal variation was typical of a small sewage‐treatment works, and the final effluent was well stabilised with average BOD and amm.‐N concentrations of 12 mg/l and 3.8 mg/l respectively.

ABSTRACTGravel bed hydroponic (GBH) systems planted withemergent hydrophytes, such as Phragmites australis (the common reed), treat domestic sewage effluents to acceptable environmental standards in an economic and efficient manner. Biochemical oxygen demand (BOD), ammonia, and coliform bacteria can be reduced by over 90% and dissolved oxygen (DO) substantially increased. In temperate zones, such as Europe, GBH systems can be used to replace conventional small rural treatment works, and for tertiary treatment of final effluents. In tropical and arid zones, GBH systems can provide locally‐managed, cost‐effective alternatives to hightechnology systems which are inappropriate for use in developing countries. Portsmouth Polytechnic reed‐bed sewage treatment GBH projects in the UK and Egypt are discussed and current progress is assessed.